In the field of electronics, applications often arise in portable equipment for a source of unidirectional voltage of limited current output. Voltage doublers and like units are known which function to minimize the weight and space necessary for batteries in such equipment, by supplying a useful voltage greater than that of the actual batteries. Such circuits traditionally comprise a continual leakage load on the batteries, even when not functioning.
Modern "reserve" batteries are available in which an electrolyte is contained in separate storage for long periods, but may be released when desired: when the electrolyte is released an interval is required for the battery to develop its full power and this interval of slowly rising voltage is unduly protracted if there is a load on the battery during the period.